1. Field of the Invention
The present invention relates to a microcomputer system including a microprocessor and a memory, and more specifically to a memory chip coupled to a microcomputer system and capable of allowing an associated microprocessor to read data and/or program from the memory chip at a high speed.
2. Description of the Related Art
At present, microprocessors have been not only of a low power consumption because of adoption of CMOS (complementary metal-oxide-semiconductor) devices, but also able to process instructions at a very high speed as a result of improvements of the architecture. On the other hand, an access to a memory for reading a program and/or data is still limited to a speed lower than an instruction execution speed of the microprocessors themselves. As a result, the total instruction execution time of the microprocessors have not yet been brought to a sufficient low value which would be realized by the speed-up of the microprocessor itself. Particularly, as in case of reading a program, when a series of instruction codes stored at continuous addresses are read out, a great portion of the processing time of the microprocessor has been consumed as a wait time for the instruction codes read out from the memory, and therefore, the processing speed of the overall microcomputer system has still been at a low level. In this connection, since the memory has been ceaselessly maintained in an operating condition, even if the microprocessor does not access to the memory, the memory will consume a substantial electric power. This is one of the causes preventing the power saving of the overall microcomputer system.